• Journal of the Korean Chemical Society
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• v.47 no.3
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• pp.283-291
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• 2003

The purpose of this research was to analyze and improve the experiment, observing the color change under compression on the equilibrium of $2NO_2\;{\rightleftarrow}\;N_2O_4$ system, described in high school and general chemistry textbooks. Chemistry textbooks described that the reddish brown color got lighter on the compression of $2NO_2\;{\rightleftarrow}\;N_2O_4$ system. This misinterpretation was due to no consideration of $NO_2$ concentration increase by the volume decrease. In order to propose a correct interpretation, the changes of color and temperature on compression were quantitatively measured and compared with theoretical studies. In addition, an improved experiment, excluding the effect of $NO_2$ concentration increase, was proposed to observe only the color change of the net equilibrium shift.

• The Journal of the Korea Contents Association
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• v.11 no.3
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• pp.262-270
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• 2011

This study examines the effects of spasticity, equilibrium and gait ability at lower extremity on lumbar stabilization exercise(LSE) with Swiss ball. This experiment was conducted to compare BBS, FRT, MAS and TUG by Swiss ball LSE with 34 stroke patients. equilibrium by BBS or FRT, spasticity by MAS and gait ability by TUG were measured after a 8-week traditional exercise physical therapy(17 subject of stroke patient) and a Swiss ball LSE(17 subject of stroke patient). These result lead us to the conclusion that BBS & FRT were statistically increased and MAS and TUG were decreased on Swiss ball LSE group. there were statistically differential effect between each group on FRT and MAS. These results suggest that Swiss ball LSE has the capability to improve spasticity, equilibrium and gait ability at lower extremity. Consequently, Swiss ball LSE would be lead to restoration of muscle spasticity, equilibrium and gait ability on stroke patients.

• Analytical Science and Technology
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• v.22 no.2
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• pp.159-165
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• 2009

The thermochromism of fluoran has been examined. The DCF exists as a colorless lactone in aprotic solvents. However, the DCF exists in the form of an equilibrium mixture of a colored zwitter-ion and a colorless lactone in protic solvents. When an acid is added to the solution, the DCF exists an equilibrium mixture as a colorless lactone and a colored cation even in aprotic solvents. In order to understand the interaction between the DCF and the solvent, absorption spectra of the DCF in various solvents were measured. The thermodynamic parameters of the DCF have also been investigated. From the variation of absorbance with temperature, the standard enthalpy changes ${\Delta}H^0$ of the equilibrium between the lactone and the zwitter-ion in various solvents have been determined. The standard enthalpy change ${\Delta}H^0$ is approximately -2.0 kJ/mol in protic solvents. In acidic solution, the standard enthalpy change is measured to be to zero in protic solvents within the experimental error. When the carboxylic group is protonated in acidic solution, a poor interaction between the dye and the solvent is expected.

• Journal of applied mathematics & informatics
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• v.31 no.1_2
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• pp.1-25
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• 2013

In this paper we have developed a mathematical model of alcohol abuse. It consists of four compartments corresponding to four population classes, namely, moderate and occasional drinkers, heavy drinkers, drinkers in treatment and temporarily recovered class. Basic reproduction number $R_0$ has been determined. Sensitivity analysis of $R_0$ identifies ${\beta}_1$, the transmission coefficient from moderate and occasional drinker to heavy drinker, as the most useful parameter to target for the reduction of $R_0$. The model is locally asymptotically stable at disease free or problem free equilibrium (DFE) $E_0$ when $R_0$ < 1. It is found that, when $R_0$ = 1, a backward bifurcation can occur and when $R_0$ > 1, the endemic equilibrium $E^*$ becomes stable. Further analysis gives the global asymptotic stability of DFE. Our aim of this analysis is to identify the parameters of interest for further study with a view for informing and assisting policy-makers in targeting prevention and treatment resources for maximum effectiveness.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.2
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• pp.101-109
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• 2002

A complex chemical equilibrium analysis was performed to study the hot-wall CVD process of the SiC/C functionally gradient materials (FGM). Thermochemical calculations of the Si-C-H-Cl system were carried out, and the effects of process variables(deposition temperature, reactor pressure, C/[Si+C] and H/[Si+C] ratios in the source gas) on the composition of deposited layers and the deposition yield were investigated. The CVD phase diagrams of the SiC/C FGM deposition were obtained, and the optimum process windows were estimated from the results.

• Journal of applied mathematics & informatics
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• v.31 no.5_6
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• pp.747-767
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• 2013

In this paper we have constructed a mathematical model of alcohol abuse which consists of four compartments corresponding to four population classes, namely, moderate and occasional drinkers, heavy drinkers, drinkers in treatment and temporarily recovered class. Basic reproduction number $R_0$ has been determined and sensitivity analysis of $R_0$ indicates that ${\beta}1$ (the transmission coefficient from moderate and occasional drinker to heavy drinker) is the most useful parameter for preventing drinking habit. Stability analysis of the model is made using the basic reproduction number. The model is locally asymptotically stable at disease free or problem free equilibrium (DFE) $E_0$ when $R_0&lt;1$. It is found that, when $R_0=1$, a backward bifurcation can occur and when $R_0&gt;1$, the endemic equilibrium $E^*$ becomes stable. Further analysis gives the global asymptotic stability of DFE under some conditions. Our important analytical findings are illustrated through computer simulation. Epidemiological implications of our analytical findings are addressed critically.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1243-1248
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• 2010

Fatigue design and evaluation of welded joints are typically carried out by weld classification approach in which a family (theoretically infinite) of parallel nominal stress based S-N curves are used according to joint types and loading modes as well as extrapolation-based hot spot stress. Traditional finite element methods are not capable of consistently capturing the stress concentration effects on fatigue behavior due to their mesh-sensitivity in stress determination at welds resulted from notch stress singularity. The extrapolated hot spot stresses tend vary, depending on the element sizes, types, joint types, and loading mode. however, the equilibrium-equivalent structural stress method(E2S2) has been recently developed through several joint industry projects as a robust method to analyze welded components using finite element analysis. This method has been proven effective in correlating a large amount of published fatigue test results in the literature such as master S-N curve and has used for evaluating the fatigue life of welding components. In this study, fatigue analysis of the welding bogie frame is examined using E2S2 method with master S-N curve.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.6
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• pp.609-615
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• 2015

This study was carried out for characterization of MIO synthesized in our laboratory by co-precipitation method and applied isotherm and kinetic models for adsorption properties. XRD analysis were conducted to find crystal structure of synthesized MIO. Further SEM and XPS analysis was performed before and after phosphate adsorption, and BET analysis for surface characterization. Phosphate stock solution was prepared by KH2PO4 for characterization of phosphate adsorption, and batch experiment was conducted using 50 ml conical tube. Langmuir and Freundlich models were applied based on adsorption equilibrium test of MIO by initial phosphate solution. Pseudo first order and pseudo second order models were applied for interpretation of kinetic model by temperature. Surface area and pore size of MIO were found $89.6m^2/g$ and 16 nm respectively. And, the determination coefficient ($R^2$) value of Langmuir model was 0.9779, which was comparatively higher than that of Freundlich isotherm model 0.9340.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.1
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• pp.61-71
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• 1999

The study aimed at the theoretical analysis of vapor sorption properties of, pp.rmaking fibers. Water vapor affinity and sorption thermodynamic properties of fiber constituents were evaluated based on Henry's law and Hildebrand's solubility theory. Theoretical equilibrium moisture content(ThEMC) on fiber surface was estimated using functional group contribution. Crystallinity of cellulose in fiber significantly controlled the water vapor solubility. Comparisons of the measured equilibrium moisture content data and the estimated ThEMC data coincidently suggested the fact that crystallinity of cellulose in fibers was around 60% to 70%. Carbohydrates constituents including amorphous cellulose and hemicellulose in fibers showed higher vapor solubility than lignin molecules. High correlation existed between ThEMC and vapor solubility as well as between ThEMC and solubility parameter. In the thermodynamic analysis on water-vapor sorption process in fibers, the sorption enthalpy increased as RH increased, whereas sorption entropy and free energy decreased with increasing RH.

• Korean Journal of Organic Agriculture
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• v.28 no.1
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• pp.31-57
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• 2020

Korea-US FTA amendment became effective January 1, 2019 through several trade negotiations between the two countries. These amendments did not include changes in the agricultural sector. However, given the policy direction of the Trump administration, it is difficult to be certain that the existing Korea-US FTA on the agricultural sector will remain unchanged. This study examines the potential impact of changes in the US beef import tariff rates under the Korea-US FTA, which is progressively eliminated until 2026 using a dynamic partial equilibrium model. The modelling system is simulated with 100% decreases of tariff rates over 2020~2026 period and then compared to the baseline which is developed based on the current Korea-US FTA tariff rates. According to the scenario analyses results, 100% decreases of US beef tariff rate lowered Korean beef cattle production value up to 4.23%. Looking at this change in terms of absolute value rather than percentage, the total production value over 2020~2026 is expected to decrease by 815 billion won compared to Baseline. This reduction in production value in dynamic analysis is 67 billion won higher than the comparative static analysis.